Sub-diffraction endoscopic modal imaging systems and methods are disclosed herein. A single multi-mode fiber endoscope incorporated into a modal imaging system can facilitate the imaging of inner portions of a patient's body at a quantum-limited resolution. One method of sub-diffraction endoscopic modal imaging includes collecting incoming radiation with a multi-mode fiber, separating the output into multiple modes, and measuring an energy level of each mode to construct an image of the received incoming radiation.
